Sheet receiving and stacking apparatus

Abstract: A sheet receiving and stacking apparatus comprising a base table (16) with a stacking section (40) for stacking a rectangular sheet (24), and guide members (50) for receiving the rectangular sheet (24) and for guiding the rectangular sheet (24) to the stacking section (40) of the base table (16); the guide members (50) having at least one movable member (19) which protrudes out on the stacking section side of the base table (16); and the movable member (19) which receives the side edge of the rectangular sheet (24) floating downwardly, retracts to the outside of the stacking section (40) under the weight of the rectangular sheet (24), and is movable to protrude again towards the stacking section side when freed from the weight of the rectangular sheet (24).

Description: BACKGROUND OF THE INVENTION The present invention relates to a sheet receiving and stacking apparatus for receiving and stacking plastics sheets and other kinds of paper which are rectangular sheets and, more particularly, is applicable to a delivery apparatus in an image forming apparatus such as a printing apparatus, for example. Generally, as a sheet receiving and stacking apparatus for receiving and stacking rectangular printed sheets, a delivery apparatus provided at the discharge section of a printing apparatus has been known. This type of delivery apparatus 1, as shown in Fig. 1, commonly has a base 6, for example a table, for receiving printed paper 3, a pair of parallel side boards 4, 4 provided generally vertically on both sides of the base table 6 in a direction in which the paper 3 is received, and an end plate 5 provided at the forward end of the base table 6 in the direction of reception of the paper 3. Both side edges of the paper 3 ejected from the printing section of the printing apparatus 2 are received between two side boards 4, 4 which are disposed parallelly, generally equal to the width of the paper 3. The leading edge of the ejected sheet 3 strikes the end plate 5 located at front and floats down to the stack section on the base table 6. In such a delivery apparatus 1, in the case of printing of a low printing rate on the paper 3, that is, in the case of a small amount of printing ink to be transferred to the paper 3, the paper 3 is discharged out of the printing apparatus 2 without changing its flat form; therefore there will occur no problem about the stacking of the paper 3 in the delivery apparatus 1. However, in the case of a high printing rate, for example when much of ink has been transferred to the paper 3 as in solid printing, the upper surface of the paper 3 to which the ink has been transferred extends largely, curling largely downwardly into an upwardly swollen form on the whole. The paper 3 discharged from the printing apparatus, therefore, will be stacked in a disorderly fashion on the base table. To solve this problem, there has been a printing apparatus 7 of known art that, as shown in Fig. 2, is provided with an auxiliary paper discharge member 8 at the inlet of the delivery apparatus 10 mounted in the paper delivery section. This auxiliary member 8 holds upwardly both side edges of the paper 9 in a direction of travel of the paper 9 being discharged from the printing apparatus 7, bending the paper 9 into the general form of U letter in the delivery state to thereby provide the paper 9 with stiffness and thereby preventing the paper 9 from being largely curled with the effect of ink and stacked on the delivery apparatus 10 in a disorderly fashion. Another apparatus which curves the paper into a U-letter form has been disclosed in Japanese Utility Model Laid-Open No. Hei 5-10367. This apparatus has a pair of side plates so disposed as to face each other at a spacing on the delivery table, a pair of guide members provided on the pair of side plates so disposed as to face each other and protrusible on the delivery table, and guide members driving means for driving the guide members by turning the guide members in synchronism with the delivery of the image forming apparatus. The conventional delivery apparatus described above, however, has the problem that both side edges of the paper 9 are partly held upwardly when the aforesaid auxiliary paper discharge member 8 is employed, but other portion of the paper 9 apart from the auxiliary paper discharge member 8 becomes free; the paper 9, therefore, is still affected by the ink to curl largely with the ink, resulting in unevenly stacked paper. In the delivery apparatus in which the guide members provided on the side plates are forced to move in and out by the guide member driving member in synchronization with the delivery of paper from the image forming apparatus, it is difficult to control the guide member driving means in accordance with the hardness of the paper, or a difference in the stiffness of the paper, which is determined by a difference in thickness and weight which depend upon the kind of the paper. Besides, the construction of the delivery apparatus required for mounting the guide member driving means will become complicated, which will cause trouble to occur and will raise manufacturing cost. JP-A-03 232 657 discloses a paper discharger for an ink-jet printer the purpose of which so to accelerate a stacked layer after ink drying up by setting up each guide plate, slidingly guiding a part of both side edges of a cutform, at both sides of an upper part of the intermediate part of a paper discharge tray, having the cutform advancing as supported by these guide plates curved with its own weight, and dropping it in the tray. At both symmetrical sides of an upper part ranging from the intermediate part of a paper discharge tray at the downstream side of a printing head to the upstream side, there is provided with a symmetrical pair of guide plates which guides both sides edges of a cutform free of travel over a length of less than half of the full length. These guide plates are made free of positional adjustment in the cross direction The cutform is printed by the printing head as being discharged by a drive roller toward the tray, and it advance as both the side edges are supported by the guide plates. With this advancement, the central part is curved with its own weight but a curing action of the cutform is adjusted by width adjustment of each guide plates so that time of up to being dropped into the tray can be shifted for adjustment. Therefore the cutform can be stacked in the tray after ink is dried up. US-A-4,794,859 discloses a sheet receiving and stacking apparatus and a method of stacking rectangular sheets according to the preambles of claims 1 and 2, respectively. The present invention is characterized by the features of the characterizing portions of claims 1 and 2. The sheet receiving and stacking apparatus for stacking paper comprises guide members which may have at least one movable member which protrudes out on the stacking section side of the base table. The moving member may receive the side edges of the rectangular sheets dropping, and withdraw outwardly from the stacking section with the weight of the rectangular sheets. Also, the movable member may so constituted as to be move outwardly again on the stacking section side when released from the weight of the rectangular sheets. The guide members may be provided in a pair, which are disposed substantially in parallel at a spacing on the base table There may be a plurality of movable members. The forward ends of the movable members, which are protruding on the stacking section side may be inclined downwardly towards the stacking section. The movable member may be rotatably provided about its support shaft so that the forward end of the movable member, which may protrude on the stacking section side, can approach the stacking section; and a turning moment on the portion of the stacking section which is outside of the aforesaid shaft and turns about the shaft as a support shaft may be greater than the portion protruding to the stacking section from the shaft. The movable members may be so constituted as to withdraw outwardly from the stacking section when the rectangular sheets are taken out. At least the stacking section of the base table of the present invention may be curved to a recess form in the surface perpendicular to the direction of discharge of the rectangular sheet from the image forming apparatus. The movable members may be designed to be selectively fixed in a position to which the movable members have been withdrawn outwardly from the stacking section. The guide members may be arranged parallel to the direction of discharge of paper to be discharged from the image forming apparatus. A sheet receiving and stacking apparatus according to a further embodiment of the present invention may have the base table provided with the stacking section for stacking the rectangular sheets and the guide members for receiving the rectangular sheets and then guiding the rectangular sheets at the stacking section of the base table, the guide members including the following members a) and b), namely: a) movable members movable between the position in which the movable members protrude on the stacking section side of the base table which receive the side edges of the rectangular sheets and the outward position of the stacking section of the base table. b) elastic members for setting the movable members in the position in which the movable members not in contact with the rectangular sheets are moved to protrude out on the stacking section side of the base table, and for allowing the movable members loaded with the rectangular sheets to move to the outward position of the stacking section of the base table. Rectangular sheets printed at the image forming apparatus are discharged onto the stacking section of the base table. The rectangular sheets are then received by the guide members, where both side edges are held in contact with the movable members of the guide members, thus bending under its own weight to a downwardly curved generally U-letter form. The movable members move away, with the weight of the rectangular sheets, towards the outside of stacking section, dropping onto the stacking section where the paper will be stacked. The movable members freed from the weight of the rectangular paper are reset to their original positions where they protrude on the stacking section side. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view showing the constitution of conventional printing apparatus and delivery apparatus; Fig. 2 is a side view showing the constitution of conventional printing apparatus and delivery apparatus; Fig. 3 is a side view of a an apparatus with features useful with the present invention; Fig. 4 is an enlarged perspective view of a major portion of the apparatus of Figure 3; Fig. 5 is a perspective view of movable members of Figure 4; Fig. 6 is a sectional view of a second apparatus with features useful with the present invention; Fig. 7 is a sectional view of an embodiment of the present invention; and Fig. 8 is a sectional view of a further apparatus with features useful with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter preferred embodiments of a sheet receiving and stacking apparatus according to the present invention will be described with reference to the accompanying drawings, by way of example only. Fig. 3 is a side view showing a printed sheet stacking apparatus with features useful with the present invention; Fig. 4 is a perspective view showing one guide means, partly omitted, in the sheet receiving and stacking apparatus of the embodiment; and Fig. 5 is a perspective view showing the constitution of a major portion of the same embodiment. To explain the present embodiment by referring to the drawings, a delivery apparatus 13 which is an apparatus for receiving and stacking paper is connected to the paper discharge side 12 of a mimeograph machine 11 which is an image forming means. The delivery apparatus 13 has an end plate 14 nearly perpendicular on the base table and movable towards the mimeograph machine 11, for stopping the leading edge of ejected sheets. Also provided nearly at right angles with the end plate 14 are a pair of side plates 15, which are movable towards the inside of the base table 16 in accordance with the size of the paper. The side plates 15 constitute a body of guide members 50 for guiding the paper to the stacking section on the base table 16. The sheet stacking section 40 is defined on the base table by these side plates 15, 15 and the end plate 14. The side plate 15 is provided with a window 17; and on a shaft 18 disposed in the inside surface is rotatably installed a movable member 19 of the guide member 50. The movable member 19 is composed of plate-like plate portions A and B mounted on the shaft 18 which serves as a base shaft. The surfaces of these plate portions A and B meet at an angle of 135°. The turning moment on the plate portion B turning on the shaft 18 as the support shaft is greater than that of the plate portion A, so that when the side edge portion of the paper rides on the plate portion A, the movable plate becomes unbalanced, easily turning to the plate portion A side. The plate portion A and the plate portion B may be formed in one unit or may be constituted of a plurality of parts. On the outside surface of the side plate 15 is provided a seat 20 for restraining the plate portion B from further turning, thus maintaining the plate portion B level while the plate portion A orotrudes to the inside of the side plate 15. According to the above-described apparatus, a paper 24 ejected from the mimeograph machine 11 is supported at both side edges on the plate portion A of the movable member 19, bending downwardly to a generally U-letter form to thereby prevent curling of the paper with the ink. Since the movable member 19 turns under the weight of the paper 24, the sheet comes off the movable member 19, floating downwardly to the stacking section 40. With repetition of this operation, the paper 24 is stacked evenly on the stacking section 40 of the base table 16. Next, the constitution and operation of another printed sheet stacking apparatus also having features useful with the present invention having a plurality of movable members will be outlined by referring to Fig. 6. As shown in Fig. 6, a pair of side plates 21, 21 parallelly disposed in opposite positions are provided each with two movable members 19, upper and lower, which are arranged at a specific spacing. The two movable members 19 provided on each side plate, although not illustrated, are arranged in two rows parallelly; that is, four movable members 19 are provided on each side plate. Each movable member 19 is mounted on a side plate opposite another movable member 19 provided in the same, corresponding position. When both edges of the printed sheet ejected from the mimeograph machine 11 come on the plate portion A of the movable member 19, the central portion of the paper 24 bends downwardly into a generally U-letter form. The paper 24 thus bent into the generally U-letter form has stiffness, and therefore it is possible to prevent curling with ink likely to occur in the case of solid printing. When the paper 24 first comes on the plate portion A of the upper movable member 19, the movable member 19 is pushed to turn downwardly with the weight of the paper 24 on the shaft 18 of the movable member 19, allowing the paper 24 to float downwardly onto the plate portion A of the lower movable member 19. With the repetition of this operation, the sheet is stacked cleanly on the base table 25 while maintaining the generally U-letter form. Fig. 7 shows an embodiment of a sheet receiving and stacking apparatus according to the present invention, that is with the base table of Fig. 6 bent in a generally U-letter form. In the following explanation, the same parts and portions as those in Fig. 6 are designated by the same numerals. The base table 26 is bent in a downwardly curved generally U-letter form; the paper 24 supported in a downwardly curved form by the movable members 19 is stacked as- curved in the downwardly curved stacking section 40a, and therefore the paper 24 ejected onto the base table will be stacked in an even further orderly fashion. Fig. 8 is a sectional view of another apparatus in which the movable members withdraw from above the stacking section 40 and which are useful with the present invention. Hereinafter operation of only one movable member mounted on one side plate will be described, which will be similarly applicable to a plurality of movable members. On the side plate 28 mounted generally squarely on the base table 27 is provided the movable member 19 as explained in Fig. 5. The plate portion B is held by the base seat 20 so that the plate portion A of the movable member 19 is maintained protruding on the inside of the side plate 28. The shaft 18 is movable from a specific position C to a retracted position D along a curved guide rail 29 provided on the side plate 28. The protruding portion of the movable member 19 which interferes with the unloading of the printed sheets from the base table 27 is moved along the guide 29 together with the shaft 18 from the position C to the position D by the printed sheets when lifted up by hand, fully retracting the protruding portion of the movable member 19 from above the stacking section 40. The printed sheets stacked evenly on the base table 27 can be taken out from the delivery apparatus. Furthermore, in Fig. 8, the base seat 20 may be designed to be movable from the illustrated position to the upper specific position, where the base seat 20 can be fixed. When the base seat 20 is fixed in the upper position, the plate portion B of the movable member 19 is raised, retracting the plate portion A fully from above the stacking section 40 and ensuring the fixing of the plate portion A in a position inside of the side plate 21. Thus the paper 24 stacked on the stacking section 40 of the base table 27 can easily be taken out. In the explanation given above, particular exemplary embodiments have been described, but the movable members are not necessarily required to be mounted directly on the guide members, nor are they required to be mechanically connected with the guide members if constructed movable from the guide members towards the paper stacking section side. For the number and arrangement of the movable members, plural rows and lines can be selected. When, however, the apparatus has a pair of parallel side plates set nearly vertically on both sides of the base table, it is desirable that the same number of movable members be provided in the same positions as the sideplates. Also it is desirable that the side plates be designed to be movable towards the center of the base table as in known manner. Furthermore, it is desirable that the base table or the paper stacking section be curved in the generally U-letter form. Each of the apparatus described above pertains to the delivery apparatus of a printing machine, but it is to be understood that the use of the present invention is not limited to the delivery apparatus of the printing machine, and the delivery apparatus may be easily selected by those skilled in the art if its object is to maintain an even stack of plastics films and other kinds of sheets. According to the above apparatus, as heretofore described, the movable members which are rotatable are able to give rigidity to even such solid-printed paper that is likely to curl due to absorption of much ink, by bending the paper to a form of generally U-letter form; and therefore printed sheets ejected from the printing machine can be stacked evenly on the base table. In each embodiment described above, the movable member of the guide member is moved outwardly of the stacking section under the weight of the rectangular sheet, and after the drop of the rectangular sheet to the stacking section, the movable member turns with its own weight back to the stacking section side. However, the movable member may be set in a specific position so that, in this position, the movable member will be able to move between the stacking section side and the outside of the stacking section, and will be pushed with an elastic member such as a spring towards the stacking section side to receive the rectangular sheet. And the movable member is constituted such that the weight of the rectangular sheet, when added to the movable member, overcomes the force of the elastic member such as the spring to move the movable member to the outside of the stacking section, so that after the rectangular sheet floats downwardly to the stacking section, the movable member can be reset by the force of the elastic member to the stacking section side.

Claims: A sheet receiving and stacking apparatus, comprising: guide members (19) for guiding a rectangular sheet (24) ejected from an image forming apparatus in a predetermined direction and a base (26) with a stacking section (40) for stacking said rectangular sheet (24) guided by said guide members (19); said guide members (19) are provided in a pair which are substantially parallel with each other at a spacing on said base (26) so as to receive both side edges of a said rectangular sheet (24); characterized in that: the positions of said guide members (19) are adjustable in a direction substantially perpendicular to the direction of discharge of said rectangular sheet (24) ejected from said image forming apparatus and substantially parallel with said rectangular sheet (24) said stacking section (40) is downwardly oriented and generally U-form in a plane perpendicular to the direction of discharge of said rectangular sheet (24) from said image forming apparatus; and wherein an end plate (14) is provided on said base (26), said end plate (14) stopping the leading edge of said rectangular sheet (24) ejected from said image forming apparatus, the position of said end plate (14) being movable in a direction of discharge of said rectangular sheet (24) ejected from said image forming apparatus. A method of stacking rectangular sheets, each having two side edges, ejected from an image forming apparatus in a predetermined direction in a sheet receiving and stacking apparatus, the method comprising: guiding each of said sheets (24) to stacking section (40) by guide members (19) receiving both side edges of said sheet the method being characterized by; adjusting, in accordance with the size of the sheets, the positions of said guide members (19) in a direction substantially perpendicular to the direction of discharge of said rectangular sheet (24) ejected from said image forming apparatus and substantially parallel with said rectangular sheet (24); stopping the leading edge of said rectangular sheet (24) ejected from said image forming apparatus by an end plate (14), the position of said end plate (14) being movable in a direction of discharge of said rectangular sheet (24) ejected from said image forming apparatus; and stacking each of said sheets (24) in the stacking section so that the sheet (20) is bent downwardly into a generally U-form. A method as claimed in claim 2 in which the method is carried out with the use of a sheet receiving and stacking apparatus as claimed in claim 1.

Inventors: KOJI NAKAYAMA, KOJI, NAKAYAMA
Applicants: RISO KAGAKU CORP, RISO KAGAKU CORPORATION
Application year: 1994
Main classification: B65H31
IPC codes: B65H29, B65H31